Archaeoraptor

Archaeoraptor liaoningensis is a hoaxed fossil that
linked dinosaurs
to birds. It was allegedly found in China in the 1990s and was described in
the November 1999 issue of National Geographic as “a true missing
link in the complex chain that connects dinosaurs to birds.” The specimen is
actually a composite of two dinosaur fossils.

According to Alex Boese,

Xu Xing, a Chinese scientist who had initially helped to
identify the fossil, was the one who eventually blew the whistle on it. He
announced that he had found a second fossil containing an exact,
mirror-image duplicate of the Archaeoraptor's tail, but attached to a
different body. Fossil stones, when taken from the ground, often cleave in
two, producing two mirror-image sets of fossil slabs. Evidently someone had
taken one of the slabs bearing the tail fossil and affixed it to a fossil of
a bird, thereby producing a hybrid dinosaur-bird creature. (Museum
of Hoaxes)

U.S. News & World Report dubbed Archaeoraptor
"The
Piltdown Chicken" and the name has stuck.

Despite claims by some
creationists that a mistake or fraud by scientists somehow supports
their belief that evolution never happened and that a god created all species
separately, most
paleontologists are convinced that birds emerged from dinosaurs. This
belief is based on strong evidence unrelated to any Chinese fossils.*

The Archaeoraptor hoax is an example of how science works.
When an error is made or fraud is committed, it is discovered and dealt with
publicly. Science is self-correcting, unlike
creationism. If this case was unusual it was due to the hoax being discovered
almost immediately after the National Geographic article appeared.
The Archaeoraptor fossil only had a few months of glory as the missing link
between dinosaurs and birds before it was exposed as a composite. We now
know that the head and body of a primitive bird and the tail and hind limbs
of a dromaeosaur dinosaur were glued together by a Chinese farmer.*

CT scans have shown that the tail and hind limbs belong to a
Microraptor zhaoianus, a small, bipedal, meat-eating dinosaur with some
bird-like features and the avian parts are from a fish-eating bird known as
Yanornis martini. "Prior to their appearance in the false
Archaeoraptor fossil, both Microraptor and Yanornis were
unknown species."*
Both are considered important new finds. They were found in the Liaoning
Province of China, "where thousands of flying and non-flying dinosaur
fossils have been uncovered. The site has provided compelling evidence
confirming the bird-dinosaur link."*